An Access Point (AP) is typically provided in a wireless access network to enable wireless client nodes to connect to a wired backhaul network. FIG. 1 illustrates a known backhaul network topology 10 for connecting all access points in a wireless access network to a backhaul network. As shown in FIG. 1, access points AP1 and AP2 each have a wired backhaul connection to an external backhaul network, such as a local area network (LAN) or the Internet. Each wired backhaul connection enables access to and from the external network in a conventional manner, e.g., by means of Ethernet links Eth0 and Eth1 to respective access switches 2, 4, and finally to a distribution switch 6. It is well known in the art that other access points, e.g., an access point AP3, can be linked to the external network in a similar fashion.
The access points AP1 and AP2 typically include at least two wireless radio transceivers for providing wireless interfaces to connect client nodes to the backhaul network via these access points. The wireless radio transceiver interfaces typically operate in accordance with the International Electrical and Electronic Engineers (IEEE) 802.11 Standard, such as version IEEE Std. 802.11-1997. According to the Standard, there are various officially published protocols, including 802.11b, 802.11g, and 802.11a. A wireless channel operating in accordance with 802.11b or 11g operates in the 2.4 GHz range. A channel operating in accordance with 802.11a operates in the 5 GHz range. In the example in FIG. 1, AP1 provides one radio for enabling client node 8 to connect wirelessly to the wired backhaul network in accordance with an 802.11b or 802.11g interface protocol. This wireless connection is identified in FIG. 1 as “11b/g”. A second radio is provided for enabling client node 12 to connect wirelessly to the wired backhaul network in accordance with an 802.11a. This wireless connection is identified in FIG. 1 as “11a” interface protocol. Similarly, second access point AP2 enables wireless client nodes 14 and 16 to connect to the wired backhaul network via an Ethernet connection Eth1 and respective wireless connections 11b/g and 11a. Although the client nodes 8, 12, 14, and 16 are each shown connected to just one computer in the example in FIG. 1, these client nodes may be connected to many computers and to other networks. The access points AP1 and AP2 each have their wireless channels 11b/g and 11a statically configured in an “access” mode for providing wireless access to the corresponding client nodes. FIG. 2 illustrates a known access point AP1 in the system in FIG. 1. The access point includes at least two radios, including one radio operating at 2.4 GHz, e.g., for 11b/g, and one radio operating at 5 GHz, e.g., for 11a. Additional 2.4 GHz radios may be provided in AP1, shown in phantom in FIG. 2.
Alternatively, one or more of the wireless channels may be operated in accordance with other suitable protocols including, for example, the 802.11n protocol (also commonly called the 11n protocol.). 801.11n is currently just a proposed protocol, the specification of which has not yet been finalized and officially published by IEEE.
A drawback of the known topology is that, if one of the wired Ethernet links fails, such as due to uplink network problems, the access point associated with that wired link will lose connection to the backhaul network. Consequently, that access point will be unable to continue to provide wireless network access to its associated client nodes. That is, no “failover” capability is provided to recover from the loss of the wired connection in topology.
FIG. 3 illustrates a known wireless mesh network topology in which an access point has one radio statically configured in an access mode and another radio statically configured in a backhaul mode. As shown in FIG. 3, an access point AP3 has one radio statically configured in an access mode for enabling a communications path with a corresponding client node 22. Access point AP3 according to topology has no direct wired connection to the backhaul network. Access point AP3 has another wireless radio that is statically configured in a backhaul mode. According to this backhaul mode, access point AP3 connects wirelessly to another access point AP4 which has a wired Ethernet link, Eth, to a backhaul switch 4. In this way, access point AP3 and access point AP4 together enable a communications path with client node 22 to enable it to have a path to the wired backhaul network.
A drawback of the wireless mesh network topology is that it does not provide failover to protect the wired backhaul connection. That is, if the wired Ethernet link Eth fails, access points AP3 and AP4, and in turn client node 22, will lose connection to the backhaul switch 4. Another drawback of topology is that one of the two radios in AP3 must be dedicated to the backhaul mode. Consequently, that dedicated radio cannot operate in an access mode to provide access service to client nodes. As a result, topology reduces the number of client nodes which can be served by the access point AP3 and reduces the total access bandwidth provided by this single access point. What is needed is an access point that provides failover capability to enable recovery from a failure of the wired backhaul connection, while providing efficient access in normal operation in order to maximize the access services to its wireless clients. Therefore, what is needed is a method and system in an access point that enables one of its radios to be selectively reconfigured from an access mode to a wireless backhaul mode in order to provide an alternative communications path to the wired network in response to detection of loss of the wired link to the access point.
What is also needed is a system and method to provide the aforementioned failover capability while only affecting the access point which lost the connection to the backhaul network and its neighbor access points, without affecting the rest of the network.